Princess Coronation 'City of London' - prone to derailments on points - seeking advice!

[Robert-370275]

Good evening,

The City of London is my first big steam train and I'm finding that there is a very high chance of it derailing when using points to change to a differing loop, eg from a curve 3 loop to a curve 2 loop.

As far as I can tell, the main culprit is the tender. It seems to want to skip over the rails. The points are set correctly and I have even tried adding some additional weight to the tender in the hope of stabilizing it, but this has made no difference.

I'm negotiating the points at a relatively slow speed and the derailments occur in both directions on nearly all of my points. The track is using DCC, so the points have the small shorting clips in them, but they are all tucked well out of the way.

I also did a very slow run whilst shining a torch between the tender and the locomotive to ensure that there is enough clearance between the two when negotiating the points and indeed, the clearance looks fine.

If I was to put a percentage on it, I'd say it is derailing around 75% of the time for any given set of points.

I was wondering if I can get any advice from the more experienced?

Is this kind of issue relatively common? Is there a trick to fixing it?

Thanks

RobP

[LTSR_NSE]

Firstly, if you run the loco (minus tender) through all the points - does it clear them all happily?

Secondly if you gently propel the tender (minus loco) through all the points - does it clear them all happily?

If the tender catches/binds/fouls by itself - can you determine exactly what/where is causing the issue?

If the loco clears fine & the tender catches on particular wheels every time, that would suggest the back-to-back of the tender wheels have been set incorrectly & need adjusting. (To do this you would need callipers or a back-to-back gauge, so check first - in case there’s a different fault.)

[96RAF]

Is the tender to loco drawbar the culprit. Is it set so the tender is running dead flat and not tending to lift either end. It is presumed that this is a loco drive model so the tender would be fairly light.

Is it any particular point in which case make sure the point is dead flat, even by way of drilling a sleeper and adding another pin right at the middle. Points have been known to bow.

[ColinB]

I have to admit this is a bit unusual these tenders are very good. I will go through the things it could be from my experience. Turn the tender over and check all the axles are in the their slots by gently pressing on them, sometimes they don't clip in properly. Check the spacing on the tender wheels, if this is out it can cause derailments. On my Coronation which is effectively the same loco I have issues with the front bogie where it didn't have enough travel, so to check this remove and run the loco to check if it still derails. The drawbars on these are usually pretty good but another issue I have had is where there is not enough travel on the drawbar, Hornby don't seem to understand that it travels up and down. To check this loosen the screw on the tender side of the drawbar, obviously you can't do this permanently but do it just to check it and run the loco and see if it derails. I quite often have to fit a screw/bolt with a longer shoulder in this case (you get them off EBay, via China). Then finally I assume this one doesn't have the new Hornby drawbar so check that the wires aren't getting snagged on the drawbar.

[Robert-370275]

Thanks for taking the time to write all the advice folks - it's much appreciated. I will run through these after work. I have to admit, it never occurred to me to separate the tender and test each individually.

I'll let you folks know if I find anything.

RobP

[atom3624]

If this is a latest tooling locomotive, it's not possible to run the locomotive on it's own - there'll be the infamous 4-pin plug into the tender.

RAF's comment is interesting - see what weight is on the tender wheels - if it's lifting.

B2B is quite critical - back to back - should be ~14.3-14.5mm between the insides of the flanges.

Check the drawbar articulation - free-moving or not - might not swing to permit the tender to negotiate the curvature of the points.

The step screws may be binding on the drawbar.

As RAF intimated, has the drawbar been bent slightly? Check all wheels 'sit' nicely on the rails. When lifting the locomotive very slowly, does the drawbar 'slop' momentarily permit the tender to continue to sit on the rails with the locomotive very partially lifted?

Al.

[ColinB]

The Stanier tender this loco uses hasn't changed much in the last 10 years, it should have a decent weight the DCC socket, screws to it. Most points are generally raised especially if they have a plastic frog, it is probably the travel on the drawbar pin. Previously Hornby allowed quite a lot of travel as I noticed today fixing a Hornby original build Clan Class but of late on new models there is virtually no travel at all.

[Robert-370275]

Hi all, I figured it out! It wasn't all the points, just one or two.

Alas, I don't know what the technical terms for the parts of the points so you will have to bear with me.

The points have a rail part that moves left and right. I discovered that when some of my points are set to take the train off of the straight line, some of my trains would derail.

It's down to the inside edge of the outer moving track piece (of the curve) not fully lining up with the fixed track at its pivoting point end. Running my finger down this inside edge revealed a sizable bump.

Manually pushing a small goods wagon down these points would cause them to derail at that bump.

To fix, I carefully bent the moving outer rail, so that its inside surface was smooth against the fix track (where its pivot point meets it) - and this did the trick! :)

If anyone actually understands what I'm saying they probably deserve a medal :)

[LTSR_NSE]

@robert - Technical terminology is superfluous when you can describe as clearly as you! :)

Very happy for you that you not only identified the fault, but resolved it as well - congratulations.

[Brew Man]

@R3

Yes, I understood what you were saying perfectly. As LT says, well done and congratulations.